1. Field of the Invention
The present invention relates to a plasma display panel and a method of driving the same and, more specifically, to a plasma display panel which is capable of decreasing a discharge firing voltage and reducing a reset period and an addressing period to improve a gray-scale representation, and a method of driving the same.
2. Description of Related Art
One example of a typical plasma display panel (hereinafter, referred to as PDP) is a 3-electrode surface discharge type PDP. The 3-electrode surface discharge type PDP includes a first substrate having a sustain electrode coplanar with a scan electrode extending in a first (or horizontal) direction; a second substrate separated from the first substrate by a certain distance, and having an address electrode extending in a second (or vertical) direction; and a discharge gas sealed between the first and second substrates. A discharge of the address electrode and the scan electrode associated with a cell of the PDP and controlled independently determines whether the cell of the PDP is discharged or not, and a sustain discharge that displays an image is then performed by the sustain electrode and the scan electrode arranged on the first substrate.
The PDP uses a glow discharge to generate visible light, and undergoes several processes until the visible light reaches human eyes after the glow discharge is generated. In other words, when the glow discharge is generated, electrons and gases are collided with each other to generate an excited gas, which generates ultraviolet (UV) light, and the UV light is collided with phosphors in a discharge cell to thus generate visible light. Further, the visible light is then transmitted through a front transparent substrate in order to reach the human eyes. Through the above-mentioned processes, an input power applied to the sustain electrode and the scan electrode is significantly lost.
In more detail, a voltage higher than the discharge firing voltage is applied between two electrodes (e.g., the sustain and scan electrodes) to generate the glow discharge. Specifically, to initiate the discharge, a significantly high voltage is needed. Once the discharge occurs, a voltage distribution between positive and negative electrodes is in a distorted manner due to a space charge effect produced in a dielectric layer around a cathode and an anode. In other words, between the two electrodes, there are provided a cathode sheath region around the cathode in which most voltage applied to the two electrodes is consumed for discharge, an anode sheath region around the anode in which a part of the voltage is consumed, and a positive column region formed between these two regions in which minimal voltage is consumed. An electron heating efficiency in the cathode sheath region depends on a secondary electron coefficient of a Magnesium Oxide (MgO) protective layer formed on the surface of the dielectric layer, and most of the input energy in the positive column region is consumed in electron heating.
A vacuum ultraviolet light (or vacuum ultraviolet) collided with the phosphors to emit visible light is generated when a Xenon (Xe) gas in an excitation state transits to a ground state, and Xe is excited due to collision of the Xe gas and the electrons. Therefore, in order to increase the ratio of generating visible light with respect to the input energy (i.e., luminescence efficiency), an electron heating efficiency should be increased to enhance collision between the Xe gas and the electrons.
In the cathode sheath region, most of the input energy is consumed but the electron heating efficiency is low, while in the positive column region, less of the input energy is consumed and the electron heating efficiency is very high. Therefore, high luminescence efficiency can be achieved with the positive column region (discharge gap).
In addition, with respect to the ratio of consumed electrons to total electrons in accordance with a change in the ratio of a gas density n to an electric field E applied between the discharge gaps (positive column region), it is known that an electron consumption ratio at the same ratio (E/n) increases in the order of Xenon excitation (Xe*), Xenon ion (Xe+), Neon excitation (Ne*), and Neon ion (Ne+). In addition, with the same ratio of E/n, as a partial pressure of Xe increases, electron energy is reduced. In other words, as the electron energy is reduced, the partial pressure of Xe is increased, and in addition, as the partial pressure of Xe is increased, a ratio of electrons consumed by excitation of Xe relative to other portions among the electrons consumed in the above-mentioned Xenon excitation (Xe*), Xenon ion (Xe+), Neon excitation (Ne*), and Neon ion (Ne+) is increased, thereby improving luminescence efficiency.
As described above, increase of the positive column region causes the electron heating efficiency to be increased. Further, the increase of the partial pressure of Xe causes a ratio of heated electrons consumed in the Xe excitation (Xe*) among the electrons to be increased to thereby further increase electron heating efficiency so that the luminescence efficiency is further improved.
However, both the increase of the positive column region and the increase of the partial pressure of Xe increase a discharge firing voltage and has a problem in that the manufacturing costs of a PDP are increased.
Therefore, in implementing the increase of the positive column region and the increase of the partial pressure of Xe to increase the luminescence efficiency, there is a need to lower a discharge firing voltage.
Also, it is known that a discharge firing voltage required for a surface discharge structure is lower than a discharge firing voltage required for an opposed discharge structure, when a distance between discharge gap and the Xe pressure for each of the structures is identical.